Improvement in automatic telegraphy



T. A. EDISON. AUTOMATIC-TELEGRAPHY.

Patented Feb. 22, 1876.

Y RRYARMYER RRSEW ER 3S: E QQH FFI THOMAS A. EDISON, OF NEWARK, NEWJERSEY, ASSIGNOR TO HIMSELF AND GEORGE HARRINGTON, OF WASHINGTON, D. G.

IMPROVEMENT m AUTOMATIC TELEGRAPHY.

Specification forming part of Letters Patent No. 173,758, dated February22, 1876; application filed January 15, 1875.-

Newark, in the county of Essex and State of New Jersey, have invented anImprovement in Automatic Telegraphs, of which the following is aspecification 1 .The object of this invention is to produce blockcharacters on chemical paper by aggregation of dots, and thetransmission is efl'ected by a strip of perforated paper, theperforations being grouped together to form the block letter, as in myPatent No. 151,209.

I make use of four lines of pertbrations in composing the block letter,four rollers or stylus-points at both the receiving and transmittingstations. The first pair of rollers are in advance of the second pair,and one roller= of one pair' and another of the other pair areconnected, and act with a positive current over the lines, and the otherrollers of the other pair act with the negative current. Thisarrangement produces the record of the letters properly in succession indots, forming block characters; but there are also produced some falsedots between the letters, that are steppedout or obliterated by hand atthe receivingstation, so that only the true characters remain visible. 7I

In the annexed diagram the receiving drums a and b, at the transmittingand receiving station, respectively, are operated as usual, and drawalong the strips of perforated paper c and chemical paper (I.-

The receiving stylus-points 1 and 3 are connected to the earth -wire 0,and the stylus points 2 and 4 are connected to the line f, andbetween-the line f and ground-wire c a small eleetro-niagnet,h, isplaced, so as to actto neutralize the static or induced current in theline, as explained in my Patent N 0. 135,531.

At the transmitting-station the rollers 5 and 7 are connected to thepositive pole of the battery I, and the rollers 6 and 8 to the negativepole, the. line-wire f being connected to the center of the battery, andthe drum' a being connected, to the earth.

Suppose, now, that four transverse perforations, composing theletter I,pass under the rollers 5 6 7 8; the roller 5 first sends a negativepulsation through the ground through 1 and 3, marking the paper,returning by 2 andi to the line, and these points 1 and 3 will mark, but2 and 4, beingqa negative return current, will not. N0.-1'is a truemark, but 3 is a false mark, that is obliterated, as illustrated in Fig.2. The roller 6 now sends a positive current over the line,.whieh goesby 2 and 4, and leaves by 3 and 1. The mark 4 is false, and isobliterated. The pulsation sent by 7 is next negative, and goes by 1 and3, and mark 3 is true, but 1 is false, and is obliterated, and then theroller 8 sends a positive current over the line by 2 and 4, returning by1 and 3. The mark 4 is the true one, and 2 is the false one; but, inconsequence of arranging the pairs of points in advance of each other,as shown, thefalse marks are brought together between the respectivecharacters, while the characters themselves stand out true and correct.

The character will be made by the pulsations as indicated, according tothe arrangement of the perforations representing that character, and thefalsemarks, being between the character, are blotted out by a boy. orattendant after the strip of paper is received from the machine, so asonly to leave the characters themselves apparent between the blots, asillustrated in Fig. 2.

I claimas my invention .Four transmitting stylus-points or rollers,connected in pairs to the positive and the negative of a battery, towhich the line-wire is united at the center, in combination with twostylus-points connected to the line and two to the earth at thereceiving-station, the

parts being arranged and operated as set forth.

Signed by me this 7th day of August, 1874.

THOMAS A. EDISON. Witnesses:

GEO. '1. PINCKNEY, CHAS. H. SMITH.

